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[924RACR]

Some general notes I've been prodded to write up, applies to street or race heads...

To give a more complete written record of recommended steps when building/refurbishing a 924 head...

Priorities for replacement of parts/cash expenditures (gaskets and seals are an obvious requirement):
#0 - new cam oiler tube elbow
#1 - new valve springs
#2 - valve job (can substitute hand-lapping valves if machining not an option)
#3 - new valves
#4 - new valve spring keepers
#5 - new valve guides

Procedure:
1 - Obviously teardown, complete disassemble, including all valves and seals, springs, etc.

2 - Clean everything; remove gaskets, scrape major carbon deposits (prefer use of green 3M nylon scrub pads or the like on aluminum surfaces, not steel wool, less erosion of material), then wash/degrease. Ideal method to wash/degrease is running through a cycle in the dishwasher; if vetoed, scrub down with nylon bristle brushes and green scrubbies in sink using dish detergent - cuts grease like no tomorrow, but easy on hands, etc.

3 - perform any needed/desired machining or modification of the head (porting, valve job, etc)

4 - assemble valves (lap if desired for optimal seal), springs, etc. Check valves for leakage by water in ports

5 - install cam, set valve clearances

6 - remaining assembly of bits and pieces

You can see it's not very technically demanding, if you keep it clean and take your time.

I also find it nice to paint the outside of the head silver - the aluminum will corrode slightly, etc, looks nicer if it's painted.

The valve springs are the most important thing (being new or in good condition) to making the top end of the motor handle high revs.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype